The present invention is in an energy saving method of melting glass in a glass melting furnace in which the charge is melted down in a melting section, while the batch of raw materials is delivered into the beginning of the melting section and fed with energy from underneath the charging end. The melted charge is then clarified in a clarifying section adjoining the melting section, then homogenized in a homogenizing section of increased bath depth adjoining the latter section, and drawn from the homogenizing section. The present invention is also in a glass melting furnace for the practice of this method, the furnace having a melting section, a homogenizing section of increased bath depth, and a clarifying section of lesser bath depth disposed between them in which burners are disposed for the input of fossil energy, the exhausting of the combustion gases and the input of the batch being performed at the beginning of the melting section.
Glass melting furnaces have a common disadvantage that despite the use of recuperators or regenerators they have a relatively low efficiency from an energy point of view. This low efficiency is not due to deficient insulation of the glass tanks, but to the fact that the furnace exhaust gas contains considerably more thermal energy than needed to preheat combustion air. There are limits to the temperature to which the combustion air can be raised, since this makes heat exchange very difficult, but the great disadvantage is especially that the concentration of the toxic nitrogen oxides greatly increases.
Various attempts have already been made to use the exhaust gas excess heat in a rational manner. One such attempt involves preheating the charge of raw materials before introducing these materials into the glass melting tank. These attempts, however, have been unsuccessful, because the heating can bring about premature fusion of some of the batch components, causing them to stick to the heat exchange surfaces. On the other hand, if the exhaust gas comes in contact with the batch not only are certain components prematurely fused, but also separation occurs or certain components of the batch are picked up by the exhaust gas, thereby unacceptably increasing the dust content in the exhaust and necessitating the use of expensive dust filter equipment.
It is an object of the invention to provide a method for melting glass, and a glass melting furnace, which will no longer suffer the above-stated disadvantages, but which will have a considerably improved efficiency, while at the same time being economical to build, and especially one in which lower NO.sub.x concentrations will be present along with a lower dust content in the exhaust, without the necessity of dealing with hot, hard-to-handle components in the furnace or in the heat exchange system.
Another object is to provide a furnace wherein the upper furnace temperatures and the temperatures in the heat exchangers (recuperators) are lower than in the commonly known furnaces.
In addition to the above-named advantages, the furnace according to the invention is to be economical to produce and safer in operation, and, in case of need, an extensive exchange of fossil and electrical energy is to be possible.